Current medical treatments generally focus on the disease and strive to eliminate the inciting agent or the symptoms, often injuring healthy tissue in the process. The present invention focuses instead on the patient, to enable self-repair mechanisms by supporting the patient's body in controlling or stabilizing its cellular functions without toxic side effects. The methods and compositions of the invention comprise phthalazinedione compounds that buffer intracellular reduction and oxidation (redox) reactions and thereby modulate cellular functions of growth, differentiation, activity, and death in various disease states.
In healthy cells, a balance of redox reactions maintains a physiologically appropriate environment for various cellular functions related to growth, differentiation, activity, and death. The proper coordination of such functions ensures homeostasis and the health of cells. Research has shown that alterations in cellular redox status affect activities such as cellular signaling, suggesting that altering the cellular redox status could also affect cellular activation, which results from certain cellular signals (U.S. Pat. No. 5,994,402). Altering the intracellular redox state by depleting cells of glutathione (GSH), an endogenous “redox agent,” has also been shown to protect cells from certain injury and to promote their survival (U.S. Pat. No. 5,994,402), again suggesting a link between alterations in the cellular redox state and cellular functions.
Stresses that perturb a cell's redox status may be internal or external. For example, a genetic mutation may produce defective protein products that function abnormally or not at all. These defective proteins could disrupt certain cellular processes, including redox reactions. Cellular redox reactions may also be disrupted by microbes, toxins, allergens, or other agents external to the cell. The external stress could trigger defensive responses that leave the cell's redox system depleted and unstable.
An imbalanced redox state, even if not the cause of a particular disease condition, may facilitate that condition by providing an “unhealthy” environment in which necessary cellular functions become impaired. Cellular redox status may become impaired in numerous disease conditions. Under the stress of a disease state, the rate of redox reactions increases or decreases as needed by the cell. Significant or prolonged deviations in the intracellular redox status disable cellular processes, including defense mechanisms. When such cellular functions are impaired, the survival of the cell becomes uncertain. Maintenance of the proper redox status is thus critical to the fate of the cell.
To counter and correct disturbances in the redox status, cells require agents that can modulate redox imbalances, to facilitate reduction or oxidation reactions as appropriate. Agents currently available for correcting redox imbalances are inadequate in that they are labile, quickly oxidized, or unable to translocate to the proper region of the cell. Examples of such exogenous redox agents include cysteine, reduced lipoates or thiols, glucocorticoids, and other antioxidants. Redox agents that remain stable, active, and functional in the cellular environment are necessary.
Although their role in modulating intracellular redox status was not recognized, phthaloylhydrazide, phthalazinedione, and phthalazine derivatives have been described as having anti-inflammatory, anti-cancer, and anti-hypoxic effects (U.S. Pat. Nos. 6,686,347; 6,489,326; 5,874,444; 5,543,410; 5,512,573; 4,250,180). However, toxicity and the lack of pharmacological activity of certain phthaloylhydrazides, including 2,3-dihydrophthalazine-1,4-dione and 5-amino-2,3-dihydrophthalazine-1,4-dione, were noted (U.S. Pat. Nos. 6,489,326; 5,543,410; 5,512,573). Luminol, also known as o-aminophthaloylhydrazide, 3-aminophthalhydrazide, 5-aminophthaloylhydrazide, or 5-amino-2,3-dihydro-1,4-phthalazinedione, was considered toxic and used in photothermographic imaging, chemiluminescent assays and labeling of cellular structures, detection of copper, iron, peroxides, or cyanides, and forensic science to detect traces of blood (U.S. Pat. Nos. 5,279,940; 4,729,950; Merck Index, 13th ed. (2001), monograph no. 5622).
Nonetheless, the compound 5-aminophthaloylhydrazide was identified for use in treating inflammatory conditions such as ulcerative colitis, Crohn's disease, diffuse sclerosis, diarrhea, proctitis, hemorrhoids, anal fissures, dyspepsia, intestinal infection, Alzheimer's disease, osteoarthritis, macular degeneration, and proctosigmoiditis (U.S. Pat. Nos. 5,874,444; 5,543,410; EP 617024; RU2211036), as well as for use in treating psoriasis, infarct, and transplant rejection (U.S. Pat. Nos. 6,489,326; 5,512,573). Other phthaloylhydrazide derivatives identified as having pharmacological activity include 2,3-dihydrophthalazine-1,4-dione, 2-amino-1,2,3,4-tetrahydrophthalazine-1,4-dione sodium salt dihydrate, 4-aminophthaloylhydrazide, 4,5-aminophthaloylhydrazide, and 4,5-methylaminophthaloylhydrazide (U.S. Pat. Nos. 6,489,326; 5,512,573; RU 2113222).
Phthalazinedione compounds, including luminol, have also been described as an inhibitor of poly (ADP-ribose) polymerase, an enzyme that responds to DNA damage (U.S. Pat. Nos. 5,874,444; 5,719,151; 5,633,282), and for treating conditions involving the functions of poly (ADP-ribose) polymerase (U.S. Pat. Nos. 5,874,444; 5,719,151; 5,633,282). A method of manufacturing the sodium salt of 5-amino-2,3-dihydrophthalazine-1,4-dione and its pharmaceutical use for immunomodulation, inflammation, and anti-oxidant treatment have been described (U.S. Pat. No. 6,489,326; RU 2222327).